This application claims foreign priority under 35 U.S.C. §119 to Belgian Application BE2014/0509 filed Jul. 3, 2014 titled “PLUNGER FOR SQUARE BALER” and having Yannic Vande Ryse and Johan A. E. Vande Ryse as the inventors. The full disclosure of BE2014/0509 is hereby incorporated herein by reference.
1. Field of the Invention
The present invention relates to agricultural balers and more specifically for plungers used in such balers.
2. Description of the Related Art
Agricultural harvesting machines, such as balers, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales.
On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc.
A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber which is then transferred to a main bale chamber. (For purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit which chops the crop material into smaller pieces.
A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes sniffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber.
In the main bale chamber, the plunger compresses the wad of crop material into flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. The plunger reciprocates, back and forth, toward and away from the discharge end of the baler. The plunger may include a number of rollers which extend laterally outward from the sides of the plunger. The rollers on each side of the plunger are received within a respective plunger first slot 82 formed in the side walls of the bale chamber, with the plunger first slot 82 guiding the plunger during the reciprocating movements.
When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is cut and the formed baled is ejected out the back of the baler as a new bale is formed.
One of the desirable outcomes in forming a bale is to have a bale with greater density of crop material. This is achieved by increasing the resistive force as the plunger compresses crop material within the main bale chamber. However, in so doing, the forces reacting on the plunger and the mechanism for reciprocating the plunger begin to increase which is not desirable for long-term operation.
US20110/0107588 describes a baler having a plunger with a pivoting point, where the pivoting point travels in the guiding channel. A linkage is provided between the plunger and a rotating drive element such that the plunger is moved forward and backwards in the guiding channel. The plunger has a face configured to have a line of loading. This line of loading shifts across the face as the linkage drives the plunger forwards and backwards in the guiding channel. The linkage directly drives the plunger without an intervening pivoting linking member, as is the case in most prior art balers. However, the line of loading from this plunger is such that first, the lower part of the newly fed crop material is compressed, and in a second phase the upper part since the rocking of the plunger starts below and moves in an upward rotation.
While others have proposed complex balers and mechanisms to reduce force applied to the plunger, they suffer from complicated mechanisms and the inevitable additional cost in an attempt to achieve such a goal.
What is needed in the art therefore, is a simplified and effective way to minimize reaction forces on a plunger while increasing bale density.